Java ObjectOutputStream writeFields（）方法与示例

ObjectOutputStream类writeFields()方法 (ObjectOutputStream Class writeFields() method)

writeFields() method is available in java.io package.
在java.io包中提供了writeFields()方法 。
writeFields() method is used to write the buffered fields to the ObjectOutputStream.
writeFields()方法用于将缓冲的字段写入ObjectOutputStream。
writeFields() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
writeFields()方法是一个非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。
writeFields() method may throw an exception at the time of writing fields.
writeFields()方法在写入字段时可能会引发异常。
- IOException: This exception may throw when getting any input/output error while writing to the output stream.IOException ：在写入输出流时遇到任何输入/输出错误时，可能引发此异常。
- NotActiveException: This exception may throw when writeObject() was not invoked to write the state of the object of classes.NotActiveException ：如果未调用writeObject()来写入类对象的状态，则可能引发此异常。

Syntax:

句法：

    public void writeFields();

Parameter(s):

参数：

It does not accept any parameter.
它不接受任何参数。

Return value:

返回值：

The return type of the method is void, it returns nothing.

该方法的返回类型为void ，不返回任何内容。

Example:

例：

// Java program to demonstrate the example 
// of void writeFields() method of ObjectOutputStream
import java.io.*;
public class WriteFieldsOfOOS {
public static void main(String[] args) throws Exception {
// Instantiates ObjectOutputStream , ObjectInputStream 
// FileInputStream and FileOutputStream
FileOutputStream file_out_stm = new FileOutputStream("D:\\includehelp.txt");
ObjectOutputStream obj_out_stm = new ObjectOutputStream(file_out_stm);
FileInputStream file_in_stm = new FileInputStream("D:\\includehelp.txt");
ObjectInputStream obj_in_stm = new ObjectInputStream(file_in_stm);
// By using writeInt() method is to write
// integer to the obj_out_stm stream
obj_out_stm.writeObject(new ReadFields());
obj_out_stm.flush();
// By using readObject() method is to read
//  object and display fields
ReadFields rf = (ReadFields) obj_in_stm.readObject();
System.out.println("obj_in_stm.writeFields(): " + rf.val);
}
static public class ReadFields implements Serializable {
static int val = 12685;
private static final ObjectStreamField[] serialPersistentFields = {
new ObjectStreamField("val", Integer.TYPE)
};
private void readObject(ObjectInputStream oin)
throws IOException, ClassNotFoundException {
// Invokes readFields()
ObjectInputStream.GetField fi = oin.readFields();
// By using get() is to get var
val = fi.get("val", 0);
}
private void writeObject(ObjectOutputStream oos) throws IOException {
// By using putFields() method is to
// write var into ObjectStreamField[]
ObjectOutputStream.PutField fi = oos.putFields();
fi.put("val", val);
// Invokes writeFields()
oos.writeFields();
}
}
}

Output

输出量